Environmental assessment request letter, February 2002

NYC 9/11 Public Portal Document 02/20/2002 09:09 FAX 2030 DEC. 4.2201 11:37pj1 JLC ENYIRONMENTAL NO.193 P.3/7

The Renaissance JLC Project# 01-2226 December 4, 2001 page 2

Intmdueftn Air sampling Is defined as the process of measuring the fitter content of a known volume of air entrained on a fitter membrane over a specified period of time. Each sample is crass -referenced by field designation and a JLC lab internal code to ensure proper, consistent handling through of custody. Sample preparation takes place within an HEPA fitter clean bench to a chain contamination. avoid any possible

Methodology Test procedures for these samples conform to the National Institute of Occupational Safety and Health (NIOSH) standards. Air sampling was conducted at a level approximating the breathing zone of persons anticipated to be present In the area during normal options. Samples collected should represent the area's typical airborne fiber concentration, All samples were collected on fully exposed 25 millimeter, 0.8 micrometer (pm) cellulose ester membrane air sampling cassettes with conductive cowl.

Analytical Procedures ~A section of the fitter approximating twenty-five percent of the total filter was removed and placed on a pre-cleaned microscope slide and then exposed to approximately 250 microliter (pi) of acetone vapor. A single 3.0 - 3.5 pl drop of triaoetin was applied and a clean #1,5 cover slip was upon the fitter. The prepared slide was then heated on a slide heater until clarity allowedplaced analysis to be conducted. Analysis was accomplished utilizing a Phase Contrast Microscope in accordance with Method, counting rule "A." NIOSH 7400

Phase Contraat Microscopy JLC Environmental's laboratory uses an Olympus BH-PC Phase Contrast Microscope, (PCM) equipped with a Walton-Beckett Grasoule. Samples were analyzed by first dissolving the fitter through a charnical process (described above) and then counting the fibers with PCM at 400x magnification. Phase contrast increases the light contrast between the object and the thus enhancing the microscopist'® ability to see fibers, Normally, 100 background, fibers are counted, whichever occurs first, microscopic fields or 100

Analytical Reuibe The "Summary of Analytical Results" represents the results of the analysis of the samples, The PCM lirnIt of reliable quantification Is less than 0.01 fibers/cubic centimeter (f/cc) do not Meet these requirements, the entire work site must be re of air. If final tests -cleaned and retested.

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